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1.
Cavitation resistance is a critical determinant of drought tolerance in tropical tree species, but little is known of its association with life history strategies, particularly for seasonal dry forests, a system critically driven by variation in water availability. We analysed vulnerability curves for saplings of 13 tropical dry forest tree species differing in life history and leaf phenology. We examined how vulnerability to cavitation (P50) related to dry season leaf water potentials and stem and leaf traits. P50‐values ranged from ?0.8 to ?6.2 MPa, with pioneers on average 38% more vulnerable to cavitation than shade‐tolerants. Vulnerability to cavitation was related to structural traits conferring tissue stress vulnerability, being negatively correlated with wood density, and surprisingly maximum vessel length. Vulnerability to cavitation was negatively related to the Huber‐value and leaf dry matter content, and positively with leaf size. It was not related to SLA. We found a strong trade‐off between cavitation resistance and hydraulic efficiency. Most species in the field were operating at leaf water potentials well above their P50, but pioneers and deciduous species had smaller hydraulic safety margins than shade‐tolerants and evergreens. A trade‐off between hydraulic safety and efficiency underlies ecological differentiation across these tropical dry forest tree species. 相似文献
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TIMOTHY J. CURRAN ROBYN L. BROWN EMILEE EDWARDS KRISTINA HOPKINS CATHERINE KELLEY ELIZABETH MCCARTHY ERIN POUNDS RENATA SOLAN JAMI WOLF 《Austral ecology》2008,33(4):451-461
Abstract Cyclones cause profound immediate impacts on tropical rainforest trees, including defoliation, limb loss, snapping of stems and uprooting. Some studies have shown that plant functional traits such as tree size, buttress roots and wood density are correlated with these forms of cyclone damage. On 20 March 2006, Severe Tropical Cyclone Larry crossed the north Queensland coast and proceeded inland across the Atherton Tablelands, impacting the critically endangered Mabi Type 5b rainforest. We investigated the effects of Cyclone Larry on common tree species by categorizing damage to trees as uprooted, snapped, limbs damaged (light, moderate, severe) or upright and estimating levels of defoliation. Damage was then related to functional traits including tree size, presence of buttress roots, wood density, and leaf size and strength. Levels of damage differed between species. Tree size (diameter at breast height) and the presence of buttress roots were not related to damage levels. Wood density was significantly negatively correlated to proportion of trees with snapped stems and significantly positively correlated with the proportion of trees upright with no or light limb damage. Levels of defoliation were significantly related to leaf strength (specific leaf area – SLA) and to leaf width, but not other components of leaf size (area or length) or petiole length. Species with high wood density and low SLA (e.g. Argyrodendron spp.) were found to have high cyclone resistance, the ability to resist damage, while species with low wood density and high SLA (e.g. Dendrocnide photinophylla) exhibited low resistance. However, traits related to low resistance are also those linked to rapid growth and high cyclone resilience, the ability to recover from damage, so it is unlikely that the Mabi forest will experience long‐term changes in floristic composition following Cyclone Larry. 相似文献
3.
Nathália da Silva Braga Angela P. Vitória Gustavo Maia Souza Claudia F. Barros Leandro Freitas 《Biotropica》2016,48(4):453-464
Wet tropical forest trees display a wide range of leaf phenology dynamics. However, the interrelation between deciduousness, water status, and leaf and stem characteristics have been poorly investigated compared with dry forests. We studied wet forest trees to answer the following questions: (1) do water regulation modes (iso/anisohydric behavior) of evergreen species differ from those found in deciduous species? (2) Does leaf water potential (ΨL) influences leaffall and emergence dynamics? (3) Are leaf and stem characteristics consistent across evergreen and deciduous trees? We evaluated vegetative phenology, ΨL, and leaf and stem characteristics of six evergreen and three deciduous species monthly for 2 yr. Species exhibited different leaffall and emergence dynamics, as well as different water regulation modes, independent of their deciduousness. Thus, the relationship between leaf phenology and water regulation behaviors appears to be a species‐specific property rather than a functional group attribute. ΨL had no direct influence on the dynamics of leaffall and/or emergence, indicating that this process is not modulated by water availability alone. Individual groups of evergreen and deciduous species could not be identified using principal component analysis (PCA), but a decoupling was observed in the leaf and stem economics spectra. The lack of an interrelation between deciduousness and iso/anisohydry, as well as the independence of leaf and stem trade‐offs, emphasizes that more systematic measurements of vegetative phenology and ecophysiological characteristics are necessary to advance our knowledge of leaf habit and water regulation behaviors based on the functional traits of wet forest plants. 相似文献
4.
Nathan G. Swenson Pedro Anglada-Cordero John A. Barone 《Proceedings. Biological sciences / The Royal Society》2011,278(1707):877-884
Explaining the mechanisms that produce the enormous diversity within and between tropical tree communities is a pressing challenge for plant community ecologists. Mechanistic hypotheses range from niche-based deterministic to dispersal-based stochastic models. Strong tests of these hypotheses require detailed information regarding the functional strategies of species. A few tropical studies to date have examined trait dispersion within individual forest plots using species trait means in order to ask whether coexisting species tend to be more or less functionally similar than expected given a null model. The present work takes an alternative approach by: (i) explicitly incorporating population-level trait variability; and (ii) quantifying the functional beta diversity in a series of 15 tropical forest plots arrayed along an elevational gradient. The results show a strong pattern of decay in community functional similarity with elevation. These observed patterns of functional beta diversity are shown to be highly non-random and support a deterministic model of tropical tree community assembly and turnover. 相似文献
5.
Jesse R. Lasky María Uriarte Vanessa K. Boukili David L. Erickson W. John Kress Robin L. Chazdon 《Ecology letters》2014,17(9):1158-1167
Theory predicts shifts in the magnitude and direction of biodiversity effects on ecosystem function (BEF) over succession, but this theory remains largely untested. We studied the relationship between aboveground tree biomass dynamics (Δbiomass) and multiple dimensions of biodiversity over 8–16 years in eight successional rainforests. We tested whether successional changes in diversity–Δbiomass correlations reflect predictions of niche theories. Diversity–Δbiomass correlations were positive early but weak later in succession, suggesting saturation of niche space with increasing diversity. Early in succession, phylogenetic diversity and functional diversity in two leaf traits exhibited the strongest positive correlations with Δbiomass, indicating complementarity or positive selection effects. In mid‐successional stands, high biodiversity was associated with greater mortality‐driven biomass loss, i.e. negative selection effects, suggesting successional niche trade‐offs and loss of fast‐growing pioneer species. Our results demonstrate that BEF relationships are dynamic across succession, thus successional context is essential to understanding BEF in a given system. 相似文献
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植物功能性状对全球气候变化的指示作用研究进展 总被引：1，自引：0，他引：1
以大气CO2浓度升高、大气温度升高、干旱胁迫加剧及紫外辐射增强为特征的全球变化对陆地生态系统产生巨大影响,植物作为陆地生态系统的重要组成部分,其功能性状对全球变化的指示作用为探寻全球变化规律、减缓气候变化提供了科学依据。该文主要综述了植物生理功能性状改变(形态变化、气孔调节、光合结构及光合途径改变和植物光合、呼吸速率及水分生理变化等)和物候功能性状改变对全球变化的指示作用,以及植物群落物种丰富度或数量增加等群落特征变化对全球气候变暖的指示作用。最后指出,完善植物功能性状指标和建立从植物个体、群落到生态系统功能的网络指示系统是今后植物功能性状指示研究的发展方向。 相似文献
9.
Background and Aims
Height gain plays an important role in plant life-history strategies and species coexistence. Here main-stem costs of height gain of saplings across species within a rainforest community are compared.Methods
Scaling relationships of height to diameter at the sapling stage were compared among 75 woody rainforest plant species in subtropical eastern Australia using standardized major axis regression. Main-stem costs of height gain were then related to other functional traits that reflect aspects of species ecological strategies.Key Results
Slopes (β) for the height–diameter (H–D) scaling relationship were close to 1·3, in line with previous reports and with theory. Main-stem volume to achieve 5 m in height varied substantially between species, including between species within groups based on adult height and successional status. The variation was largely independent of other species traits, being uncorrelated with mature plant height (Hmax) and with leaf size, and weakly negatively correlated with wood density and seed size. The relationship between volume to reach 5 m and wood density was too weak to be regarded as a trade-off. Estimated main-stem dry mass to achieve 5 m height varied almost three-fold across species, with wood density and stem volume contributing roughly equally to the variation.Conclusion
The wide range in economy of sapling height gain reported here is presumed to be associated with a trade-off between faster growth and higher mortality rates. It is suggested that wide diameters would have a stronger effect in preventing main-stem breakage in the short term, while high wood density would have a stronger effect in sustaining stem strength over time. 相似文献10.
Fire is a frequent disturbance in the tropical dry forests of Central America, yet very little is known about how native species respond to such events. We conducted an experimental burn in a tropical dry forest of western Nicaragua to evaluate plant responses to fire with respect to survivorship and recruitment. Measurements of woody vegetation of all size classes were carried out prior to the prescribed burn and three successive years post fire. We selected the 15 most abundant species <10 cm DBH to assess percent survivorship and sprouting responses post fire. Changes in seedling densities for these 15 most abundant species and the 15 least abundant species were analyzed using a repeated measure ANOVA. We also assessed changes in seedling densities for three species of international conservation concern. We found three major fire‐coping strategies among common dry forests plants: resisters (low fire‐induced mortality), resprouters (vigorous sprouting), and recruiters (increased seeding post‐fire). While survivorship was generally high relative to tropical moist forest species, those species with lower survivorship used either seeding or sprouting as an alternative strategy for persisting in the forest community. Seed dispersal mechanisms, particularly wind dispersal, appear to be an important factor in recruitment success post‐fire. Burn treatment led to a significant increase in the density of seedlings for two species of conservation concern: Guaiacum sanctum and Swietenia humilis. Results of this study suggest that common dry forest species in western Nicaragua are fire tolerant. Further study of individual species and their fire responses is merited. 相似文献
11.
Tobias Fremout Evert Thomas Hannes Gaisberger Koenraad Van Meerbeek Jannes Muenchow Siebe Briers Claudia E. Gutierrez‐Miranda Jos L. Marcelo‐Pea Roeland Kindt Rachel Atkinson Omar Cabrera Carlos I. Espinosa Zhofre Aguirre‐Mendoza Bart Muys 《Global Change Biology》2020,26(6):3552-3568
Understanding the vulnerability of tree species to anthropogenic threats is important for the efficient planning of restoration and conservation efforts. We quantified and compared the effects of future climate change and four current threats (fire, habitat conversion, overgrazing and overexploitation) on the 50 most common tree species of the tropical dry forests of northwestern Peru and southern Ecuador. We used an ensemble modelling approach to predict species distribution ranges, employed freely accessible spatial datasets to map threat exposures, and developed a trait‐based scoring approach to estimate species‐specific sensitivities, using differentiated trait weights in accordance with their expected importance in determining species sensitivities to specific threats. Species‐specific vulnerability maps were constructed from the product of the exposure maps and the sensitivity estimates. We found that all 50 species face considerable threats, with an average of 46% of species’ distribution ranges displaying high or very high vulnerability to at least one of the five threats. Our results suggest that current levels of habitat conversion, overexploitation and overgrazing pose larger threats to most of the studied species than climate change. We present a spatially explicit planning strategy for species‐specific restoration and conservation actions, proposing management interventions to focus on (a) in situ conservation of tree populations and seed collection for tree planting activities in areas with low vulnerability to climate change and current threats; (b) ex situ conservation or translocation of populations in areas with high climate change vulnerability; and (c) active planting or assisted regeneration in areas under high current threat vulnerability but low climate change vulnerability, provided that interventions are in place to lower threat pressure. We provide an online, user‐friendly tool to visualize both the vulnerability maps and the maps indicating priority restoration and conservation actions. 相似文献
12.
Cynthia L. Wright Andr L. A. de Lima Eduardo S. de Souza Jason B. West Bradford P. Wilcox 《Ecology and evolution》2021,11(17):11808
- In seasonally dry tropical forests, plant functional type can be classified as deciduous low wood density, deciduous high wood density, or evergreen high wood density species. While deciduousness is often associated with drought‐avoidance and low wood density is often associated with tissue water storage, the degree to which these functional types may correspond to diverging and unique water use strategies has not been extensively tested.
- We examined (a) tolerance to water stress, measured by predawn and mid‐day leaf water potential; (b) water use efficiency, measured via foliar δ13C; and (c) access to soil water, measured via stem water δ18O.
- We found that deciduous low wood density species maintain high leaf water potential and low water use efficiency. Deciduous high wood density species have lower leaf water potential and variable water use efficiency. Both groups rely on shallow soil water. Evergreen high wood density species have low leaf water potential, higher water use efficiency, and access alternative water sources. These findings indicate that deciduous low wood density species are drought avoiders, with a specialized strategy for storing root and stem water. Deciduous high wood density species are moderately drought tolerant, and evergreen high wood density species are the most drought tolerant group.
- Synthesis. Our results broadly support the plant functional type framework as a way to understand water use strategies, but also highlight species‐level differences.
13.
Functional traits have long been considered the ‘holy grail’ in community ecology due to their potential to link phenotypic variation with ecological processes. Advancements across taxonomic disciplines continue to support functional ecology's objective to approach generality in community assembly. However, a divergence of definitions, aims and methods across taxa has created discord, limiting the field's predictive capacity. Here, we provide a guide to support functional ecological comparisons across taxa. We describe advances in cross‐taxa functional research, identify gaps in approaches, synthesize definitions and unify methodological considerations. When deciding which traits to compare, particularly response traits, we advocate selecting functionally analogous traits that relate to community assembly processes. Finally, we describe at what scale and for which questions functional comparisons across taxa are useful and when other approaches may be more constructive. Our approach promotes standardized methods for integrative research across taxa to identify broad trends in community assembly. 相似文献
14.
Diurnal changes in water content of the stems of apple trees, as influenced by irrigation 总被引：3，自引：4，他引：3
Abstract Groups of apple trees within an orchard were irrigated by either releasing a fine mist within the canopy or spraying water on the soil. Diurnal changes in the water content of the xylem were inferred from measurements of density made with a gamma probe. Transpiration rates were estimated from leaf temperatures, and water potentials and changes in radial dimension of the stem were recorded. Xylem water content and water potential declined each morning and recovered in the afternoon. Radial dimensions of the xylem followed a similar pattern, but the percentage change was very small in relation to the change in water content of the same tissue. The decline in water content is unlikely to have been caused by cavitation, as it was readily reversed in the afternoon. It is more likely to have been caused by changes in the volume of water occupying already-cavitated fibres or intercellular spaces. Water potential and xylem water content were highest in the mist-irrigated trees and least in the unirrigated controls. 相似文献
15.
Aim Lianas are abundant and diverse throughout the world and constitute an important structural and functional component of tropical forests. This study aims to investigate liana diversity, abundance and their functional traits in Indian tropical dry evergreen forest (TDEF).Methods A total of ten 1-ha plots, one each in 10 Indian TDEF sites were demarcated. Each 1-ha plot was divided into one-hundred 10- × 10-m quadrats to facilitate woody species inventory. All lianas ≥1cm diameter measured at 130cm from the rooting point and all trees ≥10-cm girth at breast height (gbh) were recorded from the study sites to analyze the patterns of liana diversity and abundance and also to compare the contribution of lianas to the total woody species richness, density and basal area. Liana variables across the study sites were compared using one-way analysis of variance. The qualitative functional traits of inventoried lianas and trees were assessed on the field and referring to pertinent field manuals.Important findings A total of 9237 liana individuals (ranged from 408–1658 individuals ha-1) representing 52 species, 45 genera and 28 families were encountered from the 10 study sites. Liana species richness ranged from 11–31 species ha-1 in 10 sites, which averaged 23.4 (±5.7) species ha-1. The total basal area of lianas in the study sites was 7. 3 m 2 (0.20–1.76 m 2 ha-1). There was a significant variation in liana species richness, density and basal area across the studied sites. On the whole, lianas contributed 52%, 49.3% and 4.1% to the total woody species (lianas and trees) richness, density and basal area, respectively. Liana trait analysis revealed the majority (50%) of lianas belonged to brevi-deciduous type. Stem twining was the chief climbing mechanism, exhibited by 21 species (52.6% of total abundance). More than half of the liana species (34 species; 6925 individuals) had microphyllous leaves. Fleshy-fruited lianas mostly bearing berries and drupes constituted the major fruit type in the studied sites. Zoochory was the predominant dispersal mode observed in 63.4% of species. Considering the ecological and functional role of lianas in Indian TDEF, the need for conservation is emphasized. 相似文献
16.
Daniel Cunha Passos Paulo Cesar Mattos Dourado Mesquita Diva Maria Borges-Nojosa 《Studies on Neotropical Fauna and Environment》2016,51(1):19-28
We assessed the lizard assemblage from a priority conservation Caatinga area from northeastern Brazil, through a pluriannual ecological approach, to expand the understanding on biodiversity patterns of Neotropical semiarid habitats. The studied area presented one of the richest lizard faunas among Caatinga sites, being composed primarily by species typical from open landscapes. The local species composition was more similar to assemblages from adjacent Caatinga ecoregions than to those from other areas within the same ecoregion. The inventoried lizard assemblage consisted of a few common species and a majority of low abundance ones, and its overall richness and abundance did not differ between rainy and dry months. Our findings demonstrated that the composition of lizard assemblages did not match with the current proposed Caatinga ecoregions, and revealed that the studied assemblage followed a lognormal species-abundance distribution, showing no significant seasonal fluctuation in richness and abundance. 相似文献
17.
Simon Thorn Claus Bässler Markus Bernhardt‐Römermann Marc Cadotte Christoph Heibl Hanno Schäfer Sebastian Seibold Jörg Müller 《Ecology letters》2016,19(2):163-170
The species–energy hypothesis predicts that more productive areas support higher species richness. Conversely, when resources are reduced, species richness is reduced. Empirical tests of whether extinctions are predominantly caused by environmental constraints or competitive exclusion are lacking. We experimentally reduced dead wood to c. 15% of the initial amount after a major windstorm and examined changes in assembly mechanisms by combining trait‐based and evolutionary species dissimilarities of eight taxonomic groups, differing in their dependence on dead wood (saproxylic/non‐saproxylic). Species richness and assembly mechanisms of non‐saproxylic taxa remained largely unaffected by removal of dead wood. By contrast, extinctions of saproxylic species were caused by reversing the predominant assembly mechanisms (e.g. increasing importance of competitive exclusion for communities assembled through environmental filtering or vice versa). We found no evidence for an intensification of the predominant assembly mechanism (e.g. competitive exclusion becoming stronger in a competitively structured community). 相似文献
18.
Vinicius L. Dantas;Luan Carlos Silva Oliveira;Carmen Regina Marcati;Júlia Sonsin-Oliveira; 《Journal of Biogeography》2024,51(9):1801-1813
To test the hypothesis that adaptive shifts leading to the assembly of tropical savannas involved coordination between bark and wood traits and to understand the underlying mechanisms. 相似文献
19.
A common observation in tropical dry forests is the habitat preference of tree species along spatial soil water gradients. This pattern of habitat partitioning might be a result of species differentiation in their strategy for using water, along with competing functions such as maximizing water exploitation and tolerating soil water stress. We tested whether species from drier soil conditions exhibited a tolerance strategy compared with that of wet-habitat species. In a comparison of 12 morphophysiological traits in seedlings of 10 closely related dry and wet-habitat species pairs, we explored what trade-offs guide differentiation between habitats and species. Contrary to our expectations, dry-habitat species showed mostly traits associated with an exploitation strategy (higher carbon assimilation capacity, specific leaf area and leaf-specific conductivity and lower water-use efficiency). Strikingly, dry-habitat species tended to retain their leaves longer during drought. Additionally, we detected multiple strategies to live within each habitat, in part due to variation of strategies among lineages, as well as functional differentiation along the water storage capacity-stem density (xylem safety) trade-off. Our results suggest that fundamental trade-offs guide functional niche differentiation among tree species expressed both within and between soil water habitats in a tropical dry forest. 相似文献
20.
- Behavioural responses to changing environments affect community composition, so the identification of associations between environmental gradients, behavioural traits and physiological traits makes a significant contribution to the quest for trait‐based rules of community change.
- We tested the hypothesis that fish morphology and lifestyle are associated with metabolic rate, hence oxygen demand, and behavioural response to gradual hypoxia [low dissolved oxygen (DO)], using respirometry and behavioural experiments. Three species fell along different points of the fast–slow lifestyle continuum: Melanotaenia fluviatilis, a pelagic fish adapted to endurance swimming, lies at the fast end of the lifestyle continuum, while Mogurnda adspersa, a benthic fish adapted to burst swimming, lies at the other end. The benthopelagic Hypseleotris sp. has an intermediate lifestyle.
- Standard and routine metabolic rates varied strongly among the species and were associated with lifestyle according to the inequality M. fluviatilis > Hypseleotris > M. adspersa. As DO declined, aquatic surface respiration behaviour also varied significantly among the species and indicated a sensitivity to hypoxia described by the same inequality. As hypoxia ensued, changes in habitat were also linked to lifestyle, but changes in activity level among species were not neatly correlated with lifestyle.
- Overall, our experiments imply that there are significant links between morphology, lifestyle, metabolism and behavioural response to hypoxia in these three species of fish.